<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script type="text/javascript">
    var s=100
    var a='hello world'
    console.log(s)
    console.log(a)
    var animal=null
    console.log(typeof animal)
</script>

</body>
</html>